Magnetic switch



V. ZAJlC MAGNETIC SWITCH Sept. 18, 1951 2 Sheets-Sheet 1 Filed June 26, 1948 2 Sheets-Sheet 2 Fig .6

v. zAJlc MAGNETIC SWITCH Fig.5

I I u I 1m. umlor:

Vlufihslcm 2 ujig A Y 6L 1 .ration of the main contacts of the breaker.

Patented Sept. 18, 1951 MAGNETIC SWITCH Vladislav Zajic, Prague, Czechoslovakia, assignor of one-half to Czechoslovak Metal &.Engineering Works, National Corporation,

Czechoslovakia Prague,

ApplicationJune 26, 1948, Serial No. 35,310 In: Czechoslovakia July 14, 1947 9 Claims.

This invention relates to air type circuitbreak- .ersand, more particularly, to an improved arc quenching arrangementior. such circuit breakers. Whenair circuit breakers are used with. high voltages and heavy current densities,.extinguish- 'ment'of the arc, resulting from opening of the circuit breaker. under. load, presents a consider- .able. problem.

comprisesan arc chuteformed by an enclosing dielectric housing and containing interleaved .platesof dielectric material which cooperatively forman elongated meandering path for the arc.

The are is caused to enter the arc .chute by the use of arcing horns or terminals to which the potential of the circuit is transferred upon sepa- To speed the arc quenching process, the interleaved plates are so arranged that they form a V-shaped slot extending in a plane perpendicular to the arc length. The V is'so arranged that the arc,

immediately upon beingstruck, has a substantially unrestricted path in thewider or open end ofthe V.

To draw the arc'into the apex of the V so that it must follow the meandering path provided by the interleaved overlapping plates, an

arc blowout coil is provided to create a magnetic field urging the arc path toward the apex of the 'V. This coil is so arranged as to be included in' series circuit with the are as the latter is 'transferredto the arcing horns, so that a strong One factor is-the expansion of air or other gases caused: by the heat of the arc, and the cross-sec- 'tion area of the arc path must be sufficient to provide for such expansion to an extent sufiicient to prevent a destructive increase in pressure of the confined gases. Another factor is the voltage which must. be handled. The actual working vo'ltage'is determined largely by the length of. thearcing path, which is, in turn, a function of the number and amount of overlap of the interleavedplates.

sipation of the heat ofthearqwhich heatinust be absorbed and. thrown off by the quenching Still anotherifactor, is. the dischamber elements. All ofthese factors are limitations insofar as design andarrangement of the interleavedplate slot forming structure is concerned.

These several factors are advantageously provided for, andan increased capacity without increase in overall size is also provided, by the arc quenching arrangement of the. present invention. This is effected by a novel design of the interleaved dielectric quenching elements wherein the arc is forced to burn inside narrow slots alternated by spacious channels. The lengthof the arc is further increased by extending its path not only in, planes perpendicular to the normal arc path but also in planes parallel to such normal arc path.

The alternating narrow slots, and spacious channels provide for adequate'lengthening of'the arc path, and hence a higher voltage capacity, without interference with the cooling of the arc and without undue restriction of the space for gas accumulation. Furthermore, the arrangement is such that the magnetic field acts on the arc in a manner to assist the movement of'the ions of the arc in certain parts of the chamber while resisting such movement in other parts of the chamber.

With the foregoing in mind, it is an object of the present invention to provide an improved arc quenching arrangement for air circuit breakers.

Another object is to provide such an arrangement whereby the capacity ofthe circuit breaker may be greatly increased without increase in overall dimensions.

These, and other objects, advantages and novel features of the invention will be apparent from the following description and the accompanying drawings. In the drawings:

Fig. 1 is a. perspective view of one of the elements of the quenching chamber.

Fig. 2 is a transverse sectional view through the chamber.

Fig. 3 is a longitudinal sectional view-of the chamber on the line l5 of Fig. 2,

Figs. 4, 5 and 6 are transverse sectional views through the chamber of Fig. 1 taken in progression from the wider end toward the narrower end of the arc path.

Figs. '7 and 8 are transverse sectional views through alternative forms of the quenching chamber.

Referring to Fig. 1, the dielectric elements: of the quenching chamber have the general section of a railroad rail, including a base I, web Z'and head 3. On one end of each element, head3'is formed with a tapered or chamfered portion providing sloping faces 5, 5. outwardly of such portion, web 2 is bevelled or chamfered to form a sloping face 4.

The interfitting relation of the dielectric elements to form the quenching chamber may be best seen in Figs. 2 through 6, in which elements such as the arcing horns, magnetic coil, and the associated contact structure have been omitted for the sake of simplicity and as they form no part of the present invention which is directed solely to the quenching chamber or arc chute. Referring to Fig. 2, the elements are arranged in two sections with their bases, such as 9, I2 juxtaposed to form the walls of the chute. The heads, such as 6, l, of the elements of the two sets extend toward each other, and the head I of an element of one section lies between and is spaced from the webs ill, I l of a pair of elements of the opposed section so as to leave a narrow passage or slot 8 between the interleaved heads and webs. The upper surfaces of each head, together with the pair of adjacent Webs and the juxtaposed bases, such as 9, l2, define a relatively spacious channel I3.

Still referring to Fig. 2, it will be observed that the arc path includes alternated narrow slots 8 and spacious channels [3. The relatively cool walls of slots 8 effect an intensive cooling of the arc, and the spaciou channels 13 provide for liberation of the expanding gases without destructive increase in pressure.

Referring to Figs. 4, 5 and 6, due to the tapering or chamfering of the heads and webs of the elements, the initial arc path (Fig. 4) is straight, or substantially rectilinear, and uninterrupted. As the arc path is drawn toward the other ends of the elements, the path has the configuration of Fig. 5, due to the chamfered webs, and finally has the configuration of Fig. 6 wherein the arc has to meander comp etely around the interleaved heads and webs through the slots 8 and channels [3. This path requires a complete reversal of the arc current direction I as the path leads around the heads of the elements.

Thus, and as shown in Fig. 3, if the magnetic field l6 (Fig. 2) acts from left to right, the parts of the arc path within channels l3 will be driven to the right (Fig. 3) while the arc path in the centers of slots 8 (where the arc direction is reversed) will be driven to the left (Fig. 3). Consequently, the magnetic field acts against the arc flow in sections of the arc path to assist the quenching action of the meander-forming elements.

Fig. '7 illustrates an alternative arrangement of the elements, in which each head is closely adjacent a pair of juxtaposed bases to form a narrow slot I'I interconnecting a pair of spacious channels formed by adjacent webs and alternately directed heads. The same reversal of arc direction is effected with the resulting quench assist action of the magnetic field.

In Fig. 8, a further arrangement of elements is illustrated in which the heads of the elements are aligned in spaced relation to form channels l9. In this case, there is no reversal of arc direction, but there is a frictional "braking effeet on the arc in slots l9.

While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles thereto, it should be understood that the invention may be otherwise embodied without departing from such principles.

I claim:

1. In an air circuit breaker an arc quenching arrangement comprising, in combination a pair of. spaced parallel rows of identical elements; said rows extending parallel to the arcing path and the elements extending perpendicular to the arc path and each of said elements comprising a relatively wide rectangular cross-section base, a relatively narrow rectangular cross-section head, and a rectangular cross-section Web interconnecting the base and the head; the elements in each row being arranged with their bases substantially coplanar to form substantially continuous walls and the heads of the elements of each row extending toward the other row; the head of each element being .disposed between a pair of elements in the other row to form alternated relatively narrow slots and relatively spacious gas expansion channels defining a meandering arc path; the arc path in at least a portion of each slot turning sharply at an angle of at least to the overall direction of the arc path through the arrangement; the slots being defined by surfaces of the heads and the channels being defined by webs of adjacent elements.

2. An arc quenching arrangement as claimed in claim 1 in which the webs and heads of said elements are chamfered on the ends toward the entrance to the arrangement to form an uninterrupted arc path converging to such meandering ath as the arc is drawn from the entrance into the arrangement.

3. In an air circuit breaker an arc quenching arrangement comprising, in combination a pair of spaced parallel rows of identical elements; said rows extending parallel to the arcing path and the elements extending perpendicular to the arc path and each of said elements comprising a relatively wide rectangular cross-section base, a relatively narrow rectangular cross-section head, and a rectangular cross-section web interconnecting the base and the head; the elements in each row being arranged with their bases substantially co-planar to form substantially continuous walls and the heads of the elements of each row extending toward the other row; the

head of each element being disposed between a pair of elements in the other row to form alternated relatively narrow slots and relatively spacious gas expansion channels defining a meandering arc path in which the direction of arc current flow is reversed in at least two planes normal to each other, the arc path in at least a portion of each slot turning sharply at an angle of at least 90 to the overall direction of the arc path through the arrangement; the slots being defined by surfaces of the heads and the channels being defined by webs of adjacent elements.

4. In an air circuit breaker an arc quenching arrangement comprising, in combination a pair of spaced parallel rows of identical elements; said rows extending parallel to the arcing path and the elements extending perpendicular to the arc path and each of said elements comprising a relatively wide rectangular cross-section base, arelatively narrow rectangular cross-section head, and a rectangular cross-section web interconnecting the base and the head; the elements in each row being arranged with their bases substantially coplanar to form substantially continuous walls and the heads of the elements of each row extending toward the other row; the head of each element being disposed in closely spaced relation to the heads and webs of a pair of adjacent elements in the other row to form alternated relatively narrow slots and relatively spacious gas expansion channels defining a meandering arc path in which the direction of arc current flow is reversed in at least two planes normal to each other, the arc path in at least a portion of each slot turning sharply at an angle of at least 180 to the overall direction of the arc path through the arrangement; the slots being defined by such closely spaced surfaces and the channels being defined by webs of adjacent elements.

5. An are quenching arrangement as claimed in claim 4 in which the webs and heads of said elements are chamfered on the ends toward the entrance to the arrangement to form an uninterrupted arc path converging to such meandering path as the arc is drawn from the entrance into the arrangement.

6. In an air circuit breaker an arc quenching arrangement comprising, in combination a pair of spaced parallel rows of identical elements; said rows extending parallel to the arcing path and the elements extending perpendicular to the arc path and each of said elements comprising a relatively wide rectangular cross-section base, a relatively narrow rectangular cross-section head, and a rectangular cross-section web interconnecting the base and the head; the elements in each row being arranged with their bases substantially co-planar to form substantially continuous walls and the heads of the elements of each row extending toward the other row; the head of each element being disposed in closely spaced relation to the bases and webs of a pair of adjacent elements in the other row to form alternated relatively narrow slots and relatively spacious gas expansion channels defining a meandering arc path in which the direction of arc current flow is reversed in at least two planes normal to each other, the arc path in at least a portion of each slot turning sharply at an angle of at least 90 to the overall direction of the arc path through the arrangement; the slots being defined by such closely spaced surfaces and the channels being defined by webs of adjacent elements.

7. An arc quenching arrangement as claimed in claim 6 in which the webs and heads of said elements are chamfered on the ends toward the entrance to the arrangement to form an uninterrupted arc path converging to such meandering path as the arc is drawn from the entrance into the arrangement.

8. In an air circuit breaker an arc quenching arrangement comprising, in combination a pair of spaced parallel rows of identical elements; said rows extending parallel to the arcing path and the elements extending perpendicular to the are path and each of said elements comprising a relatively wide rectangular cross-section base, a relatively narrow rectangular cross-section head, and a rectangular cross-section web interconnecting the base and the head; the elements in each row being arranged with their bases substantially co-planar to form substantially continuous walls and the heads of the elements of each row extending toward the other row; the head of each element being disposed in closely spaced row aligned relation to the heads of a pair of adjacent elements in the other row to form alternated relatively narrow slots and relatively spacious gas expansion channels defining a meandering arc path, the arc path in at least a portion of each slot turning sharply at an angle of at least to the overall direction of the are path through the arrangement; the slots being defined by such closely spaced surfaces and the channels being defined by webs of adjacent elements.

9. An arc quenching arrangement as claimed in claim 8 in which the webs and heads of said elements are chamfered on the ends toward the entrance to the arrangement to form an uninterrupted arc path converging to such meandering path as the arc is drawn from the entrance into the arrangement.

VLADISLAV zAJic.

REFERENCE S CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,306,204 Boehne Dec. 22, 1942 2,393,164 Hobson Jan. 15, 1946 2,442,199 Dickinson May 25-, 1948 

